POS0736 PREVALENCE AND RISK FACTORS OF FRAGILITY FRACTURES IN SYSTEMIC LUPUS ERYTHEMATOSUS: A LONGITUDINAL STUDY OVER 12 YEARS
Authors: C. C. Mok, K. L. Chan, L. Y. Ho, C. H. To
Journal: Annals of the Rheumatic Diseases (2022)

Objectives To study the prevalence and risk factors of fragility fractures in a longitudinal cohort of patients with systemic lupus erythematosus (SLE). Methods All patients who fulfilled ≥4 1997 ACR criteria for SLE and have been registered in our cohort database since 1990 were included. Symptomatic fragility fractures, defined as those that occurred with no preceding injury or after a low-energy impact, were identified from the SLE organ damage index (SDI) data and verified by record review. A longitudinal cohort of 383 SLE patients who participated in a cross-sectional study in 2011 and had a baseline dual energy x-ray absorptiometry (DEXA) scan performed was further analyzed for factors predicting new fragility fractures over time. These patients were stratified into 2 groups according to the presence of previous fragility fracture or osteoporosis at baseline, defined as a DEXA T score &lt;-2.5 or Z score &lt;-2.0 at the hip, femoral neck or lumbar spine. The cumulative incidence of new fractures was studied by Kaplan-Meier’s analysis and risk factors were studied by Cox regression, adjusted for demographic characteristics, medications and other confounding factors. Results 1140 SLE patients were included (age of onset 34.7±14.4 years; 91.5% women). 102 fractures (hip [n=15]; vertebral [n=54]; limbs (non-hip) [n=14]; digital/rib [n=19]) developed in 91(8.0%) patients over a mean of 13.1 years. The prevalence of major osteoporotic and hip fractures was 0.56 and 0.10 per 100 patient-years, respectively. A cohort of 383 SLE patients were further analyzed (age at DEXA scan 40.5±13 years; 94% women). Osteoporosis was present in 105 patients (13 with past fractures) at baseline and 8 other patients had osteopenia but a history of fragility fractures. Patients with osteoporosis/previous fractures (N=113), compared to those without (N=270), were more likely to have SLE onset during childhood (&lt;18 years), longer SLE duration and a higher prevalence of thrombocytopenia, hemolytic anemia or neuropsychiatric manifestations that required immunosuppressive therapies. Use of glucocorticoids (79% vs 62%; p=0.002) and mycophenolate mofetil (MMF)/azathioprine (AZA) (55% vs 42%; p=0.02), body mass index (BMI) ≤18kg/m2 (14% vs 7%; p=0.04) or menopause before the age of 45 years (14% vs 4%; p=0.001) were also more frequent in the osteoporosis/fracture group. However, no difference in the SLEDAI scores at time of DEXA scan was observed between the 2 groups (3.7±3.8 vs 4.1±3.3; p=0.26). Over a follow-up of 153±41 months, new symptomatic fragility fractures developed in 34(8.9%) patients (vertebral [n=19], hip [n=2], limbs (non-hip) [n=6], digital/rib [n=7]; incidence 0.69 per 100 patient-years). The cumulative risk of new fragility fractures at 3,5,10 and 15 years was 1.8%, 3.7%, 14.7%, 22.2%; and 1.5%, 1.9%, 3.9%, 6.7%, respectively, in the osteoporosis/previous fracture and non-osteoporosis groups (log rank test; p&lt;0.001). Cox regression showed that older age (HR1.08[1.03-1.12]; p=0.001), osteoporosis/previous fracture (HR3.47[1.59-7.59]; p=0.002) and a family history of fracture (HR4.31[1.41-13.2]; p=0.01) at baseline were independently associated with the development of new fractures after adjustment for confounding factors. SLE duration, childhood onset disease, low BMI, chronic smoking, premature menopause, use of glucocorticoids, MMF, AZA or hydroxychloroquine, anti-Ro positivity, history of thrombocytopenia, hemolytic anemia and neuropsychiatric manifestations were not significant risk factors for new fractures. In those patients using glucocorticoids at baseline, there was no significant relationship between the daily dosage of prednisolone and new fractures. Conclusion In a longitudinal cohort of SLE followed for over 12 years, new fragility fracture developed in 8.9% of patients. Increasing age, osteoporosis, a personal or family history of fractures were major risk factors. Disclosure of Interests None declared